Problem: $\dfrac{6}{3} - \dfrac{9}{10} = {?}$
Solution: $ = {\dfrac{6 \times 10}{3 \times 10}} - {\dfrac{9 \times 3}{10 \times 3}} $ $ = {\dfrac{60}{30}} - {\dfrac{27}{30}} $ $ = \dfrac{{60} - {27}}{30} $ $ = \dfrac{33}{30}$